Sound producer



March 24, 1931. QSKELLEY 1,797,349

SOUND PRODUCER Filed June 18, 1950 INVENTOR CECIL SKELLEY ATTORNEY Patented. Mar. 24,1931

UNITED STATES PATENT OFFICE CECIL S. KELLEY, EAST MCKEESIPORT, PENNSYLVANIA, ASSIGNOR TO THE WEST- ING-HOUSE AIR BRAKE COMPANY, OF WILMERDING, PENNSYLVANIA, A CORPQRA TION or PENNSYLVANIA SOUND PRODUCER Application filed June 18,

This invention relates to sound producing devices, and more particularly to the type employin a vibratory diaphragm.

Hereto ore it has been proposed to equip .5 the flexible diaphragm of sound producing devices with a weight so that a more positive opening and closing movement of the diaphragm will be obtained. One type of sound producing device having a weighted 1 diaphragm is shown in United States Letters Patent No. 1,679,011, of R. G. Widmyer, issued July 31, 1928. In the structure shown in. the above mentioned patent, the weight is riveted to the diaphragm, and on each side of the rivet, the surface of the weight facing the diaphragm is cut away on an are, so as to permit flexing of the diaphragm. With such construction, the arched surface of. the

, weight does not meet the face of the diaphragm tangently when the diaphragm is flexed away from its normal position. As a result of this, constant vibration of the diaphragm often results in a fracture of the diaphragm at the point where the face of the diaphragm meets the arched face of the weight when the diaphragm is flexed outwardly from its normal position.

It has also been proposed to provide sound producing devices of the type herein referred to with means for limitin the flexing of the diaphragms outwardly rom their normal positions, when the diaphragm's'are vibrated. One type of sound producing device having means for limiting the vibration of the diaphragm is shown in United States Letters Patent No. 1,742,380, of Clyde 0. Farmer,

issued January 7, 1930.

In the Farmer device, stops are provided at the rear side of the diaphragm. The use of these stops, it'has been found, reduces the tone volume considerably, and also destroys the tone quality to a certain extent, and in addition, does not entirely eliminate the diaphragm breakage. Furthermore, the stops f may dig into a diaphragm andthus cause breakage at thispoint.

An object of the invention is to provide a sound producing device having a weighted diaphragm in which the weight is formed 1930. Serial No. 461,961.

with a weight which is so mounted on the diaphragm that it provides a stop for limiting the movement of the diaphragm outwardly from its normal position.

Another object of the invention is topro vide an improved sound producing device of the character mentioned which is simple in construction, and reliable and exact in function under all conditions of service.

The invention also comprises certain new and useful improvements in the construction, arrangement and combination of the several parts of which it is composed, as will be hereinafter more fully described and claimed.

In the accompanying-drawing; Figure 1 is a section of a sound producing device embodying the invention, showing the flexible diaphragm in the normal inoperative position; and Fig. 2 is a view similar to Fig. 1, showing the diaphragmflexed outwardly to ililustrate the maiimer in which the diap ragm engages t e'wei ht. 1

Referring to-the drawing, the sound pro- 'ducing device may comprise a casing 6 having a chamber 7, which is open to a flexible diaphragm 8, said diaphragm being clamped in POSitIOD by a cover plate 9, wh ch is secured to the casing 6 by screws 10.

The casing is provided. with a central tube 11, which projects inwardly toward the diaphragm 8. Secured to the tube 11 is a suitable amplifyin horn 12. When the parts are assembled, t e free end of the tube 11 justenglgges 1the face of the diaphragm 8, as shown. 1n 1g. i

The chamber 7 is connected to a pipe 13, throughwhich fluid under pressure is supplied to said chamber, the rate of flow. being governed by a restricted port 14 formed in .the casin 6 between the end of the pipe an vide a central fiat surface 20, of less diameter than the diameter of the base of the weight, for bearing against the inner face of the diaphragm. A stop 18 is formed at the inner end of the undercut portion of the weight, and at the outer periphery of the base of the weight, there is a corner 19, the purpose of which will be hereinafter more fully described.

*In operation, when fluid under pressure 'is supplied to pipe 13, fluid flows through the restricted port 14 into chamber 7, and the pressure of fluid in chamber 7 builds up so that the diaphragm 8 is'moved outwardly.

In moving out, communication is opened from chamber 7 to the space within the tube 11. The pressure in said chamber is then quickly reduced, since the rate of flow through the restricted port 14 is considerably less than the rate of fiow from chamber 7 to tube 11. The pressure on the diaphragm 8 I being thus relieved, said diaphragm returns to its position engaging the end of the tube 11. The opening movement is then repeated.

The diaphragm is thus caused to vibrate and thereby produces a sound which is amplified by the usual operation of the horn 12.

The weight 16 makes it necessary for the fluid pressure to be built up to a higher point before the diaphragm will move away from the end of the tube 11, than would be the case 'with an unweighted diaphragm, but when the diaphragm does move, the higher pressure causes a greater movement of the diaphragm and consequently, a greater amount of potential energy is stored up, so that the return movement of the diaphragm is efi'ected more forcibly.

In this action, it is desirable to provide means for limiting the outward movement of the diaphragm 8, so that the rebound of the diaphragm will be dampened. This is accomplished by so forming the weight 16, that when the diaphragm moves outwardly, the inner face of the diaphragm will engage the outer edge or corner of the base of the weight,

as shown in Fig. 2.

is small, and therefore the deflection of the diaphragm outwardly, is also small, so that the inner face of the diaphragm enga es the periphery of the base 0 the weig t efore the'elastic limit of the diaphragm 1s reached.

Since the diaphragm 8 normally engages the surface 20 of the weight, when the diaphragm moves outwardly and strikes the periphery of the base of the weight, a greater surface of the diaphragm will be engaged, and therefore the movement of the diaphragm is arrested. However, if the force of the diaphragm is great, the diaphragm will deflect slightly further, due to the momentum of the weight, before returning to its normal position. In this way the movement of the diaphragm willbe gradually arrested when the periphery ofthe base of the weight is engaged. Therefore, the use of the periphery of the weight as means for arresting the outward movement of the diaphragm provides a resilient stop, because when the face of the diaphragm engages the corner 19 of the weight, if the force of the diaphragm is great, the diaphragm will be deflected slightly further before returning to its normal position against the inner end of the tube 11.

While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A sound producing device comprising a casing having a chamber, a flexible diaphragm subject to the pressure of fluid 1n said chamber. a vent tube normally in engagement with said diaphragm, a welghted member carried by said diaphragm for regulating the vibratory movement of sald dlaphragm, and means on the weighted member for dampening the movement of the dlaphragm.

2. A sound producing device comprising a casing having a chamber, a flexible diaphragm subject to the pressure of fluid 1n sald chamber, a vent tube normally in engagement with said diaphragm and controlling communication from said chamber to sald tube, and a weighted member in the form of a truncated cone, for regulating the vibratory mgvement of said diaphragm away from the tu e.

3. A sound producing device comprising a casing having a chamber, a flexible diaphragm subject to fluid in said chamber, a vent tube normally in engagement with said diaphragm and controlling communication from said chamber to said tube, and a weighted member mounted on the diaphragm, the face of the member adjacent the diaphragm being under cut to provide means for arresting the movement of said diaphragm when the diaphragm is deflected from said tube. v

4. A sound roducer comprising a flexible diaphragm ad under pressure, and a member mounted on ope side of said diaphragm for controlling the operation thereof, said member having two substantially parallel base portions of different areas for engaging said diaphragm, one of said portions being always in engagement with the diaphragm and the periphery of the other portion being adapted to engage with the diaphragm when the diaphragm is flexed.

In testimony whereof I have hereunto set my hand, this 16th day of June, 1930.

CECIL S. KELLEY.

apted to be operated by fluid 

